The most abundant coal resource in western North America and Canada is the low rank coals, which include sub-bituminous coal and lignite. Many deposits of these coals are relatively easy to mine; but, unfortunately, they contain large amounts of moisture. High levels of moisture result in low calorific values for the coal. Coal with high levels of moisture not only costs more to transport, but substantially more if it must be combusted for a given heat output.
The higher-rank coals, many of which are found in the Eastern United States, suffer from another disadvantage--they often contain substantial amounts of ash. The ash, in addition to lowering the calorific value of the coal, will cause erosion of boilers when the coal is burned and pollution of the environment. Environmental regulations necessitate the use of expensive ash-recovery facilities.
A similar problem exists with crude oil, particularly heavy crude oils. There are substantial reserves of heavy crude oil in Western Canada and Venezuela; the reserves of heavy crude oil in Venezuela are believed to be at least equal to the known recoverable reserves of conventional crude oils in the rest of the world. This oil generally has an American Petroleum Institute ("A.P.I.") gravity of less than about 10. Petroleum refiners prefer to work with crude oils with an A.P.I. of at least about 20, for such oil is substantially more economical to process to much higher value products.
Processes for reducing the moisture content of coals are well known to those skilled in the art.
Thus, for example, in 1923, in U.S. Pat. No. 1,477,642, Benjamin Gallsworthy disclosed that certain low grade crude petroleums contained a substantial amount of moisture. Gallsworthy taught a process in which the oil was sprayed over heated lignite and allowed to percolate through the lignite. The lignite used in Gallsworthy's process had to be substantially moisture-free prior to the time it was contacted with the oil.
In 1926, in U.S. Pat. No. 1,574,174, Eugene Shoch disclosed a process in which fresh lump lignite is heated in a still while immersed in thin petroleum oil. Shoch taught that, in general, such lignite should not be heated to a temperature in excess of 300 degrees Centigrade, stating that (at page 1) "Fresh lignite . . . frequently contains . . . from 25% to 35% of moisture, which it loses when heated at 110 degrees C. . . . Heated above this temperature, to 300 degrees C., it gives up still more moisture, and some carbon dioxide; and heated still higher it begins to yield tar, and some combustible gases; the deepseated decomposition which it then undergoes involves an exothermic reaction so that the heating power of the products when used as a fuel is less than that of the original material . . . ."
In 1932, in U.S. Pat. No. 1,871,862, Eugene Shoch again disclosed that, when lignite is heated to a temperature in excess of 300 degrees Centigrade, it undergoes an exothermic reaction.
In 1939, yet another lignite dehydration patent was issued to Eugene Shoch. In U.S. Pat. No. 2,183,924, Shoch disclosed that lignite is subject to disintegration when it is dehydrated, stating that (at page 1) " . . . when lignite is heated in dryers or retorts to remove this moisture, it also undergoes such extensive disintegration." In the process of this patent, Shoch submerged the lignite under a hydrocarbon oil while maintaining both within a closed vessel, and he heated the contents of the closed vessel to a maximum temperature of from 200 to 220 degrees Centigrade.
In 1952, in U.S. Pat. No. 2,610,115, Henry Lykken disclosed a method for dehydrating lignite. In the first step of this process, the lignite was crushed and then screened to a size not substantially exceeding 1 inch mesh. Thereafter, the screened lignite was mixed with from 3 to 10 percent of a mineral hydrocarbon oil. Thereafter, the lignite/oil mixture was heated to a maximum temperature of 300 degrees Fahrenheit.
In 1957 Lykken was issued another lignite dehydration patent. In U.S. Pat. No. 2,811,427 he again disclosed a process in which a lignite/oil mixture was heated to a maximum temperature of 300 degrees Fahrenheit.
A third lignite dehydration patent (U.S. Pat. No. 2,966,400) was issued to Lykken in 1960. In the process of this patent, coarsely crushed and screened lignite was fed with a minor amount (3-10 weight percent) of fluidal hydrocarbon material into and through a rotary preheating kiln, and then into and through a rotary processing kiln in which the temperature of the lignite is raised to about 600 degrees Fahrenheit.
In 1972 U.S. Pat. No. 3,754,876 was issued to Robert E. Pennington et al. The patentees disclosed a process for removing water from sub-bituminous or lower rank coal in which the coal is contacted with a "stream of inert hydrogenpoor hydrocarbonaceous heat transfer fluid . . . ." At column 3, the patentees taught that the fluid used in their process must have a hydrogen-to-carbon ratio of less than 1.5. They also teach that petroleum oils, which generally have higher hydrogen-to-carbon rations (1.5 to 2.0), should not be used in the process of their invention.
In 1976, in U.S. Pat. Nos. 3,985,516 and 3,985,517, Clarence Johnson disclosed a process in which particulate pyrophoric low rank coal was contacted with from 0.5 to 5 percent of hydrocarbon liquid while in a fluidized bed and while being heated to a temperature of from 250 to 500 degrees Fahrenheit.
In 1980, in U.S. Pat. No. 4,213,752, Walter Seitzer disclosed a lignite dehydration process in which the coal was passed into a moving bed of hot coal at a temperature in the range of from about 200 to about 300 degrees Centigrade.
In 1982, in U.S. Pat. No. 4,309,192, Isao Kubo et al. disclosed a process for the treatment of "water-containing coal." In the first step of this process, a mixture of such coal and a hydrocarbon oil is provided. Thereafter, such mixture is heated at a temperature of from 100 to 350 degrees Centigrade.
In 1984, in U.S Pat. No. 4,461,624, Brian Wong disclosed a process for improving the calorific value of lowrank coal. In the first step of this process, the coal was crushed to a particle size of 0.1 to 3 centimeters. Thereafter, the crushed coal was immersed in a distillation residuum of petroleum crude oil at a temperature of from 240 to 350 degrees Centigrade.
In 1985, in U.S. Pat. No. 4,504,274, Ardis Anderson disclosed that dried coal has a " . . . tendency toward spontaneous combustion . . . " which presents " . . . a serious problem during the shipment and storage of such coal . . . ." In the process of this patent, a "coal spray" is used to coat the dried coal.
In 1985, in U.S. Pat. No. 4,547,198, James Skinner also disclosed that " . . . the dried coal produced by such processes frequently had a tendency to undergo spontaneous ignition and combustion in storage and transit . . . ." In order to minimize this pyrophoricity, Skinner passed the coal through a mist of oil.
In 1986, in U.S. Pat. No. 4,571,174, Walter Shelton disclosed that, in a fluidized bed, dried low rank coal has a tendency to ignite. At column 1 of hs patent, Shelton taught that: "The coal leaving a drying process for the removal of inherent water will typically be at a temperature of from bout 130 to about 250 degrees Fahrenheit. . . . When such processes for the removal of inherent water are applied to low rank coals, the coal has a tendency to ignite in the fluidized bed as a result of the contact between the high temperature gases normally used as a hot fluidizing gas to dry the coal and coal particles which have been dried to a relatively low water content."
It is an object of this invention to provide a process which enables one to simultaneously improve the fuel properties of coal and oil.
It is yet another object of this invention to provide a process for reducing the amount of moisture in coal.
It is yet another object of this invention to provide a dried coal which is substantially non pyrophoric.
It is yet another object of this invention to provide a dried coal with a substantially higher heating value than the parent coal from which it is derived.
It is yet another object of this invention to provide a dried coal which is substantially non deliquescent.
It is yet another object of this invention to provide a process for reducing the amount of sulfur in oil.
It is yet another object of this invention to provide an oil which has a substantially higher A.P.I. gravity than the parent oil from which it is derived.